Special Separator Solutions - FMC Technologies

Subsea separation projects experience numerous challenges with regards to equipment design and efficiency both during installation and operation. With our compact separators, efficient separation is achieved as a part of the subsea separation system; performing primary separation at the seabed thus reducing the topside footprint, increasing the oil recovery rate and total oil production. The special separator solution can be combined with other compact CDS equipment to achieve secondary separation.

PipeSeparator

Featuring a pipe segment of standard pipe code dimension which acts as a long, slender separator, the PipeSeparator is especially suited for efficient oil-water separation in subsea applications. This innovative technology does much the same job as a conventional separator vessel for separating oil and water, but since the smaller pipe size withstands the external water pressure far better than a large vessel it can also be used in very deep waters. The PipeSeparator has proved to be very robust towards varying gas loads and slugging. For high gas load applications, a device may also be used at the inlet of the PipeSeparator to dampen slugs and remove bulk free gas from the liquid stream. By itself or in combination with a water polishing solution, the PipeSeparator can supply high quality water that is suitable to be routed directly for re-injection into the reservoir. The technology has been developed in cooperation Statoil and can handle a wide range of liquid and gas loads, oil API’s and water cuts. The concept has been extensively tested with live crude oil at real field temperature and pressure conditions, and is currently being designed and built for installation at the Petrobras Marlim field in Brazil.

For separation purposes, the PipeSeparator has a number of advantages over a conventional multiphase separator vessel:
•The small diameter leads to a much shorter droplet sedimentation distance
•The relatively high bulk velocity gives increased shear forces across the emulsion layer which helps break the emulsion layer down
•The small diameter gives a relatively much larger interfacial area for the phases to pass through, increasing separation efficiency

MultiPipe

The MultiPipe separator is a compact subsea gas-liquid separation solution based on proven onshore solutions for pipe slug catcher design. It has significantly lower weight and smaller volume compared to other technologies.

The basic principle of the pipe based separation system is to distribute the gas/liquid two-phase flow into several parallel pipe sections. This makes it possible to increase the total cross sectional flow area in the separator to reduce the fluid velocity and at the same time keep a short settling distance for the liquid droplets. Short droplet settling distance has in general a favorable effect on the efficiency and quality of gas-liquid separation. The separation principle is much the same as what happens in a horizontal separator. The MultiPipe separator can be designed according to pipe code and compared to pressure vessels the required wall thickness will be considerably reduced. Furthermore, the piping could also be integrated as a part of the subsea structure. Each of these factors represents a potential weight and cost reduction.

Currently, FMC Technologies are performing extensive testing of the concept at realistic production conditions. The tests will also involve a number of secondary separation solutions in combination with the MultiPipe.